Superabsorbent polymers (SAPs) are synthetic polymer materials having a capacity to absorb 500 to 1000 times their own weight in moisture. Although developed for practical use in sanitary items, SAPs now find additional applications in a variety of fields including as disposable diapers for children, sanitary pads, raw materials in soil conditioners for horticulture, water stopping agents for civil engineering and construction applications, sheets for raising seedlings, freshness preservatives for food distribution, goods for fomentation, and the like.
In practice, however, SAPs are now used, for the most part, for diapers for urine absorption, but not in sanitary pads for women because urine and menstrual blood are quite different from each other as to the physical properties thereof. Containing salts, proteins and cells as well as water, menstrual blood is so highly viscous that it does not readily diffuse. In addition, large cell masses are not absorbed into SAPs, but form a film on the surface, which serves as a barrier to the absorption of blood. For these reasons, SAPs are used only in small amounts in sanitary pads. Thus, there is a need for a novel approach to the development of SAPs exhibiting improved blood absorption.